Maritime officials are reporting new attacks by Somali pirates, while the United Nations says high-seas bandits have collected millions of dollars in ransom payments over the past year.

Officials Thursday said two Yemeni vessels and 22 Yemeni fishermen were captured Wednesday in the Gulf of Aden. Seven fishermen managed to escape on a smaller boat.

Speaking in Kenya Thursday, the U.N. envoy for Somalia Ahmedou Ould-Abdallah said he believes pirates may have collected over $120 million this year, with "total impunity."

Ould-Abdallah called on countries that can do so to trace and freeze the assets of the pirates' financial backers.

Somali pirates have hijacked some 40 ships this year and currently hold about 15 vessels and their crews, despite a growing number of international patrols to stop the attacks.

U.N. diplomats say the U.S. has circulated a draft Security Council resolution proposing that all nations and regional groups chasing pirates off the Somali coast be allowed to follow them onshore, on land and in the air. The text stipulates that Somalia's transitional government would need to give its consent.